Your skin performs a variety of functions for you that are crucial for your overall health. It helps you regulate your body temperature, keeps things in place, and gives us the experiences of touch (including pain). Your skin protects you against attacks from the outside.
It’s also a protective layer that shields your body from germs, and preserves the body’s internal homeostasis. Just exactly how does it do that? With the Lipid Barrier.
What Is a Lipid?
A lipid is a molecule or compound that is not soluble in water. Think of things like animal fats and plant-derived oils that are “greasy” and don’t mix with water. There are many types of lipids found in the body. Cholesterol and triglycerides are two you may have heard of. Fatty acids are another.
While “lipid” is often used as a synonym for fats, fats are actually triglycerides (a subgroup of lipids).
Where Are Lipids Found in the Skin?
Lipids are found throughout the skin.
- Sebum is the oily substance secreted by the sebaceous glands attached to hair follicles.
- All cell membranes incorporate lipids.
- In the granular layer of the epidermis, free fatty acids, cholesterol, and sphingolipids are released from keratinocytes that are in the process of breaking down into corneocytes.
- Lipids are essential to the stratum corneum layer (the outermost layer) of the epidermis. This is the layer that we are most interested in today.
What Is the Lipid Barrier?
The skin barrier is also referred to as the lipid barrier, since lipids play such a vital role in its function. The skin barrier, or barrier function refers to the outermost stratum corneum layer. It is put together and functions something like a brick wall, as described by Peter M. Elias M.D., of the University of California, San Francisco, an expert on skin barrier and epidermal biology.
Imagine the structure of a brick wall:
- The bricks are made up of corneocytes, which are dried out, deceased skin cells that are ready to be shed (dander).
- The mortar is the cement that holds the bricks together. It’s comprised of an intercellular matrix of lipids that surround each corneocyte.
The three major types of lipids making up the mortar are sterols (specifically, cholesterol), ceramides, and free fatty acids. The fact that the fatty acids have extremely long chains of carbon is what makes them so hydrophobic. In order for the barrier to work efficiently, these lipids are organized into specific membrane structures that also must include linoleic acid.
Why Is the Lipid Barrier Important?
As with any good, solid, sturdy brick wall, this barrier is generally impermeable. Only very specialized molecules get in. Almost nothing but water gets out (transepidermal water loss, or TEWL). With healthy skin, water is not massively lost out of the skin, and harmful irritants or microorganisms are not allowed entry, ensuring that healthy skin stays hydrated, firm, and soft.
Without a competent skin barrier, life on terrestrial earth wouldn’t be possible for more than just a couple of hours.
When this permeability barrier fails, the other important functions of the skin fail, too. The ability to withstand injury due to friction, the ability to prevent invasion by bacteria and other microbes, and the prevention of the uptake of foreign materials are all closely tied to the competence of the barrier function.
What Happens When the Lipid Barrier Is Damaged?
There are multiple reasons and causes of a damaged barrier function, but the symptoms are all pretty easy to spot. Dry, flaky, itchy, irritated, or sensitive skin are common signs of a damaged or weakened barrier function.
If any of the three essential lipid classes is deficient or not present in a 1:1:1 molecular ratio, the result is disorganized regions that are “leaky.” They provide an outlet for loss of water from the body and the entry of other molecules from the outside. When the skin is dried out it can become more permeable to irritants and allergens. Once these penetrate the epidermis, they may trigger inflammation, leading to a vicious cycle.
How to Keep a Strong Barrier Function
Since a strong barrier function is the cornerstone to healthy skin, it’s important to pay attention to its care.
- Stay away from allergens and harsh products like irritating chemicals, solvents, or detergents. Even excessive use of perfumes can weaken the barrier.
- Since exposure to hot water, steam, or high heat will strip lipids from the skin, avoid those when you can.
- Excessive cleansing with soap can remove the lipids as well as the natural moisturizing factors in the stratum corneum, decreasing the ability of the skin cells to stay together. Don’t overdo it. Avoid exfoliating too often, too.
- Avoid conditions that cause sensitivity like dry air, bitter cold, and strong winds.
- Protect the lipids from breakdown by using sunscreen religiously and products that contain antioxidants.
If you’re looking to repair damage that has already been done, look for ingredients that will replace lipids that have been lost.
I’ve created SciaEssentials® DELTA-5® to effectively improve the skin’s barrier function. It contains linoleic acid plus sciadonic acid, a key fatty acid, to help build and improve the skin’s ceramide structure. Not only that, but it also helps to decrease molecules that cause inflammation of the skin, helping to break the cycle.